Electron tube



F. HERRIGER ELECTRON TUBE Sept. 16, 1941.

Filed July 29, 1939 Felix Her rgger Attorney,

Patented Sept. 16, 1941 ELECTRON TUBE Felix Herriger, Berlin, Germany,

assignor to C.

Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a company Application July 29, 1939, Serial No. 287,199 In Germany August 4, 1938 1 Claim.

This invention relates to electron tubes, and more particularly to those designed for ultrahigh frequency amplifiers, in which two pushpull operating electrode systems together with two neutralization systems which are adapted to simulate the impedance of the systems are enclosed in a single vacuum vessel.

These tubes are intended for the amplification of ultra-short waves, especially in the waveband under three meters. It is shown herein that in the electron transit tim between cathode and grid, attenuation occurs in the grid circuit, and very strongly hinders the efficient amplification of the tube.

The present invention discloses a means for the elimination of this disadvantage through the use of an oxide cathode in a tube of the aforementioned nature together with a space-charge grid surrounding the cathode.

It is known that the positive attenuation of the grid-cathode path can be changed into negative attenuation when a tube is employed having a characteristic which can be represented by a power function of the form i=K-u", where 2' is the space or anode current, u is the anode voltage, and K is a constant depending upon the tube construction and in which the exponent n is smaller than Such a characteristic is shown by space-charge grid tubes and by tungsten cathodes near the saturation point. The former or space-charge grid tubes are most important in the present problem, for, in tubes constructed according to my copending U. S. application Serial No. 229,245, filed September 10, 1938, the cathode will only emit electrons in this latter manner.

Figs. 1 and 2 show, in cross-section, plan views of tubes constructed in accordance with my invention.

In the accompanying Figure 1 a possible application of such a tube is shown in cross-section. This device follows the teaching of the above-mentioned copending application in that the electrodes and leads are positioned and connected so as to be self-neutralizing and includes, furthermore, between the cathode Kl or K2 having thereon electron emissive layers BI and B2, respectively, and control grid GI or G2, a space-charge grid RI or R2, which is brought to a certain positive potential so that a characteristic is obtained, the exponent n of which is smaller than 72. According to the known theory a characteristic of the form i=K-u is obtained.

It is important for the trouble-free operation of the device that the space-charge grid be of no greater high-frequency voltage than the cathode. It is therefore proposed that the two adjoining space-charge grids operating push-pull in the same system be arranged with respect to one another to give the least possible inductive effect. This can, for example, with reference to Fig. 2, be accomplished with a wide strip I, which connects the adjacent grid supports of the space-charge grids RI and R2 along their entire length. The control grids GI and G2 are open on one side and held in place by the special supporting rods 2 and 3.

What is claimed is:

An electron tube comprising two electrode systems adapted for push-pull operation, said electrode systems being arranged to be selfneutralizing systems and comprising two cathodes and two anodes, one of said electrode systems including one of said anodes and one of said cathodes, and a space-charge grid surround- 4 ing each of said cathodes, and connecting means for interconnecting said space-charge grids.

FELIX HERRIGER. 

